Our loyalty is due entirely to the United States. It is due to the President only and exactly to the degree in which he efficiently serves the United States. It is our duty to support him when he serves the United States well. It is our duty to oppose him when he serves it badly.

Theodore Roosevelt (1858–1919) American politician, statesman, conservationist, writer, US President (1901–1909)

Essay (1918-04-06), “Citizens or Subjects?” Kansas City Star
    (Source)

Regarding a bill which had just passed the Senate Judiciary Committee which would fine and imprison any one who used "contemptuous or slurring language about the President."

This passage was added to later editions of his essay, "Lincoln and Free Speech,", as printed in The Works of Theodore Roosevelt, vol. 21, The Great Adventure, ch. 7 (1925). It does not appear in the original version of the essay or book. See Roosevelt and Roosevelt.